Sometimes Unity is treating C# compile time Warnings as compile time Errors

Sometimes, most of the times after switching from Visual Studio back to Unity after changing some code and pressing play, Unity treats a C# Warning like a C# error and it prevents you from compiling or running the game before that Warning has been fixed.

It doesn't happen all the time though.

The warning is also written in red in the Console, just like a C# error. In the same console message, all the C# warnings in my project are also written (in red).

An example warning which Unity is sometimes treating as an error is: Assets/MyClassXYZ.cs(47,22): warning CS0168: The variable `someVariable' is declared but never used

Unity doesn't let you run the game before you go and fix the Warning.

Is this happening to anyone else?

 

I have never seen something like that.

 

I had this problem antyviurs very often cause this. Disable antyvirus or reinstal unity

 

Do you have an smcs.rsp or gmcs.rsp file in your Assets folder? Warning-as-error can be turned on in that file with the line:

-warnaserror+

We always have it turned on.

 

I've seen this problem when the compiler couldn't create the output DLLs in the Temp/ folder because the output file was locked by some other process. This goes along the lines of what Breyer suggests. Can happen with Dropbox, too. In these cases, the full text output of the warning message when you select it in the console shows an error when you scroll further down. Not ideal that the two get mixed up and it looks as if the warning made the compile fail.